Peel and chop the onion and garlic. Clean, wash and roughly dice the zucchini. Peel, wash and chop the potatoes.
Heat the oil in a large pot. Sauté the onion and garlic until transparent. Add zucchini and potatoes and fry briefly. Season with salt and pepper. Stir in 1 l water and stock. Bring everything to the boil, cover and simmer for about 15 minutes.
Finely puree the soup with a hand blender. Season to taste with salt and pepper. Crumble the gorgonzola roughly. Serve soup with cheese and crème fraîche.